An in-wheel working device including: a stator fixed to the inside of a housing, a rotor rotatably installed in the stator, a rotating part rotatably installed in the housing, and rotated with the rotor, a resolver fixing part fixed to the inside of the housing, and a resolver moving part. The resolver moving part includes a resolver rotor positioned outside the resolver fixing part and facing the resolver fixing part, and a cover part fixed to the rotating part and covering the resolver rotor.